Hey- chew on this! We’ve made it to the.. The Digestive System
Gastrointestinal System • Function-physical and chemical breakdown of food • Includes alimentary canal and accessory organs • Accessory organs: Salivary glands, tongue, teeth, liver, gallbladder, and pancreas
Alimentary canal • Mouth- physical and chemical breakdown. • Mastication-the act of chewing • Saliva contains enzyme amylase to break down carbohydrates
Pharynx- contains opening to trachea as well. Epiglottis covers opening of trachea. • Esophagus-muscular tube dorsal to trachea • Relies on a rhythmic wave-like motion called peristalsis
Sphincter-a circular muscle that constricts a passage or closes a natural orifice (opening) • Cardiac sphincter • Pyloric sphincter • Food sits in stomach for 1-4 hours. Gastric juices contain hydrochloric acid- activates pepsin, kills bacteria.
Small intestine: not so small! 20ft x 1’’ • Duodenum- 1st 10 inches. Bile and pancreatic juice enter here • Jejunum- next 8 ft. • Ileum- final 12 ft. When food leaves small intestine, digestion is complete
Small intestine has lots of enzymes: peptidases • maltase, sucrase, lactase, amylase. • Lipase • Bile Digested food is absorbed into the bloodstream.
Large intestine- 5 ft x 2’’. Separated from small intestine by ileocecal valve • Final absorption of water, storage of indigestible material, absorption of vitamins B and K by bacteria. • Colon connects to rectum- anal canal opens to the anus (final opening). Fecal material is expelled.
But Wait! What about the accessory organs: Liver, gall bladder and pancreas • Liver- largest gland in your body • Secretes bile- emulsifies fat, makes them water soluble. • Stores glucose in the form of glycogen • Makes clotting proteins • Detoxifies blood
Gall bladder- stores and concentrates bile • Pancreas- produces insulin, pancreatic juices amylase and lipase. Insulin regulates the uptake of glucose by the cells
Diseases • Appendicitis • Cholecystitis- gall bladder • Cirrhosis- destruction of liver cells • Diarrhea • Diverticulitis • Gasteroenteritis • Hernia • Pancreatitis • Liver transplant • Ulcer • Colitis • Bariatric surgery